Bracket on rear of F Superduty Dana 80

[ISPKI]

Hey all. I was cleaning up the underside of my 94 F Super duty prepping to flush out the rear axle and I noticed an odd looking bracket assembly bolted to it.

There is a steel bracket bolted next to the rear diff cover. That bracket has a sort of pivot pin with a banana shaped bar leading to another pivot pin, another banana bracket, and then into some kind of module thing that has a brake line feeding into it.

I have never seen this thing before and the banana shaped brackets are not connected. Looks like the clevis pin fell out.

Is this some kind of ABS for the F Superduty? I have googled everything I can think of but finding clear info on these trucks is a big PITA.

 

[CharlesG]

That's a proportioning valve for the rear brakes.

 

[1mouse3]

That's a proportioning valve for the rear brakes.

For a proportioning valve, I see a brake load one.

http://www.diesel-dave.com/vehic/manual/svo/svo66014.htm
http://www.diesel-dave.com/vehic/manual/svo/svo60029.htm

 

[ISPKI]

Got a picture of it.

Proportioning valve eh? Never seen one set up like this. Whats the point of the lever and what would happen if it were connected vs disconnected?

 

[CharlesG]

The valve is load-dependent. Heavier loads allow more rear brake effort. If disconnected, the rear brakes could lock up or have little effect.

 

[Big Bart]

Think of it as a mechanical ABS VS todays computerized ABS.

The closer the frame/bed is to the axle, the more brake pressure is allowed through the valve. (More weight more braking.) The further the frame/bed is going up (Bed is going up as the front end goes down during braking.) the less brake pressure. Helps with rear lock up during braking.

If undone perhaps try hooking up to see what happens. (It could be good, or it could be bad, stuck, etc.)

If good leave it hooked up. (Maybe was not unhooked on purpose.)

If bad then perhaps you will want to lock it in a position that gives you good braking with your standard load. (Rear's barely lock up at full and hard stopping.) So adjust then figure out how to lock in place.